The present invention relates generally to an apparatus for producing screws or the like fastening devices, and more particularly to improvements in a machine for pointing pilot ends of screw blanks or the like prepared by cutting a length of bar stock into pieces of a predetermined size wherein said pilot ends are pinch-pointed by means of a pair of forging dies.
In the production of screws or the like, it has been customary to form a continuity of rough blanks from a length of wire stock between a pair of forging dies, thereafter forming a head section and a shank section with each of the blanks by forging and simultaneously cutting the continuity of those blanks into pieces by forcibly nipping them between the dies, as disclosed in U.S. Pat. Nos. 2,652,577 and 2,740,136. However, according to these methods, a length of bar stock or material is utilized to produce therefrom a desired shape of screws or the like, consequently causing inefficiency as well as high expense in production.
Thus, according to current knowledge in the art, a pinch-pointing machine is employed wherein, prior to the step of forming pilot ends with screws, a desired size of headed blanks are prepared by cutting a length of bar stock into pieces, then the headed blanks are supplied to the pinch-pointing machine to form the pilot ends on the screws, as disclosed in U.S. Pat. Nos. 3,398,413 and 3,758,900. However, the pinch-pointing machines disclosed therein utilize a pair of dies wherein one of them is fixed in position while the other is mounted to a reciprocable die-head so that the latter die is movable back and forth with respect to the former die thereby to forge blanks between the dies. According to this construction, however, each of the blanks cannot be supplied to a center C.sub.1 between the two dies as illustrated in FIG. 19, since one of the dies is stationary. As a result, accurate forging cannot be effected and the screw ends formed thereby are not precise in dimension and configuration. Further, the unbalanced arrangement of the pair of dies causes undesirable vibrations and noise in operation, since the plastic deformation of the blanks carried out by one of the dies is not equal to that by the other. Thus, one of the dies wears out more rapidly than the other and therefore must be replaced with new ones after a short span of life, resulting a discontinuance of further pinch-pointing operations, causing a waste of time and labor.
Further, in such a particular case of the conventional nail end pointing machine as disclosed in U.S. Pat. No. 3,717,891, a dial feed mechanism is provided for supply nail blanks intermittently to a forging position between a pair of movable dies which are adapted to squeeze each of the blanks from both sides with equal pressure. However, according to the construction of the machine therein disclosed, the feed mechanism is not provided with an adjusting means for adjustably feeding each of blanks to an accurate center position between the pair of movable dies, wherein centering of feeding blanks must be achieved by adjustably setting the dies, which requires a high degree of skill and a lot of time and labor. If this adjustment is performed imperfectly or inaccurately, the blanks are held unsteady between the dies, this adversely affects the accuracy of the forged products and the life of the dies.
Therefore, an object of the present invention is to eliminate the above-discussed prior art deficiencies.
Another object of the present invention is to provide an improved type of pinch-pointing machine wherein a pair of forging dies are adapted to be relatively accessible from both sides in order to squeeze each blank therebetween with equal pressure when the dies are moved to contact with each other, and mechanism is provided which permits minute adjustment for accurately feeding each blank to a center position between the dies thereby to make it possible to readily and exactly adjust the position of the blanks to the dies, with the additional advantages of enhancing the accuracy of the forging formation as well as balancing the machine, and subsequently for reducing the vibrations and noises in the machine.
A further object of the present invention is to provide an improved pinch-pointing machine which is designed to facilitate double forging or repeated pinch-pointing operation on each single blank.
A still further object of the present invention is to provide an improved pinch-pointing machine wherein a pair of movable dies are arranged so as to increase the durability thereof.
A further object of the present invention is to provide an improved pinch-pointing machine which permits employment of a pair of dies which are easy to manufacture.
Other objects, features and advantages of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.